Purpling of my plant

Hey guys! So i bought a seed that was supposed to make a bright purple plant but only (and all) the caliss (idk of thats the right name but the things from which the pistils stick out) Were supposed to turn purple. The problem is that the only ones that turned purple are the ones where the light does not penetrate well. So my question is this: is it becoming purple because only the green light (which penetrates well and plants that absorb it are generally red) or is it because there is not much light and it’s a result of stress and i should put the plant in the dark for a while for it to purple up?
Other useful infos:
- i use a 250w led growlight and i’m at around 7-8
-weeks of flower
-the recommended time of flower is 2 months
- the last time i watered (on the 23 of may) i only used water
- i recently had a calcium deficiency which might have slowed things down but i solved it

I’m sorry this is such a messy thread but it’s not even clear in my own head